RESUMEN

This study investigates the dynamics of a modified Colpitts oscillator, exhibiting complex periodic and chaotic behaviors. Our research explores the dynamics and synchronization of coupled chaotic Colpitts oscillators, crucial for understanding their potential applications and behaviors. The main discovery is the emergence of a phase in which the systems achieve either complete synchronization or desynchronization. This behavior depends on the values of the coupling parameter. The subsequent challenge involves understanding how the coupling parameter influences the emergence of this synchronization phenomenon.

RESUMEN

The dynamics of competing opinions in social network plays an important role in society, with many applications in diverse social contexts such as consensus, election, morality, and so on. Here, we study a model of interacting agents connected in networks in order to analyze their decision stochastic process. We consider a first-neighbor interaction between agents in a one-dimensional network with the shape of ring topology. Moreover, some agents are also connected to a hub, or master node, who has preferential choice or bias. Such connections are quenched. As the main results, we observed a continuous nonequilibrium phase transition to an absorbing state as a function of control parameters. By using the finite-size scaling method we analyzed the static and dynamic critical exponents to show that this model probably cannot match any universality class already known.

RESUMEN

We study the synchronization of two coupled idealized economies. In the present work, we consider a recently developed economic system that shows a richness of dynamical behavior. By means of the Lyapunov exponents, we analyze that there is overly complex behavior in the transitions in the dynamics of an isolated economy, oscillating between chaotic attractors and limit cycles. Then, for two coupled economies, we analyze the synchronization states for the space of all control parameters as a function of the network coupling parameter. Interestingly, we have evidenced that there is a broad region of fully synchronized states and as we increase the coupling, some phenomena such as a smooth and intermittent loss in synchronization emerge. In the same way, we observe phase synchronization for one of the control parameters. Ultimately, in order to confirm this loss of synchronization, we inspect the stability of synchronized states through the master stability function method for some control parameters. Here, we corroborate what was previously observed, the unexpected vast range of control parameter values of instability corresponding to desynchronization.

RESUMEN

OBJECTIVES: This study aimed to perform a cost-effectiveness analysis (CEA) of the molecular diagnostic method (MM) associated with conventional diagnostic method (CM) compared with the CM alone, for the detection of resistant profile in bacteremia, from the perspective of the Brazilian Public Health System, in intensive care units setting. METHODS: The clinical parameters regarding methicillin-resistant Staphylococcus aureus (MRSA), carbapenem-resistant Gram-negative bacteria (CRGNB), and vancomycin-resistant Enterococcus spp. (VRE) infections were collected from searches on PubMed, Scopus, and SciELO, using specific keywords. Data on direct medical costs to treat these infections were collected according to Brazilian Public Health System perspective from Brazilian databases, in tables of 2018 to 2019. CEA was performed after building a dynamic model, which was calibrated and validated according to international recommendations. The incremental cost-effectiveness ratio of the MM + CM compared with the CM was calculated using the outcomes "avoided death" and "avoided resistant infections." One-way sensitivity analyses were performed. RESULTS: This CEA demonstrated that the MM + CM was dominant in all scenarios. Estimates showed that for MRSA, CRGNB, and VRE infections, every avoided death would lead to savings of Brazilian real (R$) 4.9 million ($937 301), R$2.2 million ($419 899), and R$1.3 million ($248 919), respectively. The same infections assessed by avoided resistant infections savings were projected to be R$24 964 ($4686), R$40 260 ($7558), and R$23 867 ($4480). CONCLUSIONS: MM leads to cost reduction and increased benefits, optimizing the use of financial resources on the health system in the intensive care unit setting, in bacteremia caused by MRSA, CRGNB, and VRE.

Asunto(s)

RESUMEN

BACKGROUND: To analyze costs associated with dementia based on a cross-sectional study in the Brazilian health system. METHODS: Direct and indirect costs were estimated by conducting comprehensive interviews on the use of resources in a sample of 156 patients with dementia treated at an outpatient memory clinic of a tertiary hospital. A regression model was used to determine the main determinants of costs associated with dementia. RESULTS: Global costs of dementia were US$1,012.35; US$1,683.18 and US$1,372.30 per patient/month for mild, moderate and severe stages, respectively. Indirect costs ranged from US$536.62 to US$545.17 according to severity. Dementia costs were influenced by medication, FAST score, and educational level of caregiver. DISCUSSION: The study represents an original contribution toward establishing direct and indirect costs of dementia in Brazil. Results indicate significant economic impacts, including projection of annual costs of US$16,548.24 per patient.

Asunto(s)

RESUMEN

Socio-economic related properties of a city grow faster than a linear relationship with the population, in a log-log plot, the so-called superlinear scaling. Conversely, the larger a city, the more efficient it is in the use of its infrastructure, leading to a sublinear scaling on these variables. In this work, we addressed a simple explanation for those scaling laws in cities based on the interaction range between the citizens and on the fractal properties of the cities. To this purpose, we introduced a measure of social potential which captured the influence of social interaction on the economic performance and the benefits of amenities in the case of infrastructure offered by the city. We assumed that the population density depends on the fractal dimension and on the distance-dependent interactions between individuals. The model suggests that when the city interacts as a whole, and not just as a set of isolated parts, there is improvement of the socio-economic indicators. Moreover, the bigger the interaction range between citizens and amenities, the bigger the improvement of the socio-economic indicators and the lower the infrastructure costs of the city. We addressed how public policies could take advantage of these properties to improve cities development, minimizing negative effects. Furthermore, the model predicts that the sum of the scaling exponents of social-economic and infrastructure variables are 2, as observed in the literature. Simulations with an agent-based model are confronted with the theoretical approach and they are compatible with the empirical evidences.

RESUMEN

The evolutionary mechanisms of energy efficiency have been addressed. One important question is to understand how the optimized usage of energy can be selected in an evolutionary process, especially when the immediate advantage of gathering efficient individuals in an energetic context is not clear. We propose a model of two competing metabolic strategies differing in their resource usage, an efficient strain which converts resource into energy at high efficiency but displays a low rate of resource consumption, and an inefficient strain which consumes resource at a high rate but at low yield. We explore the dynamics in both well-mixed and structured populations. The selection for optimized energy usage is measured by the likelihood that an efficient strain can invade a population of inefficient strains. It is found that the parameter space at which the efficient strain can thrive in structured populations is always broader than observed in well-mixed populations.

RESUMEN

Cooperation plays an important role in the evolution of species and human societies. The understanding of the emergence and persistence of cooperation in those systems is a fascinating and fundamental question. Many mechanisms were extensively studied and proposed as supporting cooperation. The current work addresses the role of migration for the maintenance of cooperation in structured populations. This problem is investigated in an evolutionary perspective through the prisoner's dilemma game paradigm. It is found that migration and structure play an essential role in the evolution of the cooperative behavior. The possible outcomes of the model are extinction of the entire population, dominance of the cooperative strategy and coexistence between cooperators and defectors. The coexistence phase is obtained in the range of large migration rates. It is also verified the existence of a critical level of structuring beyond that cooperation is always likely. In resume, we conclude that the increase in the number of demes as well as in the migration rate favor the fixation of the cooperative behavior.

Asunto(s)

RESUMEN

A system of nearest neighbors Kuramoto-like coupled oscillators placed in a ring is studied above the critical synchronization transition. We find a richness of solutions when the coupling increases, which exists only within a solvability region (SR). We also find that the solutions possess different characteristics, depending on the section of the boundary of the SR where they appear. We study the birth of these solutions and how they evolve when the coupling strength increases, and determine the diagram of solutions in phase space.